Website is down or not accessible from some computers or browsers but works fine from others

From some browsers or computers, attempting to navigate to the NetCommunity main URL results in a blank screen. However, other users, or the same user working in a different browser, may be able to access the site without problems.This may be accompanied by the following error when attempting to view individual pages themselves:

System.Net.WebException: The request failed with HTTP status 503: Service Unavailable.